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//
// A rust binding for the GSL library by Guillaume Gomez (guillaume1.gomez@gmail.com)
//

use ffi;
use std::mem::zeroed;
use enums;

/// This routine computes the exponential integral E_1(x),
/// 
/// E_1(x) := \Re \int_1^\infty dt \exp(-xt)/t.
pub fn E1(x: f64) -> f64 {
    unsafe { ffi::gsl_sf_expint_E1(x) }
}

/// This routine computes the exponential integral E_1(x),
/// 
/// E_1(x) := \Re \int_1^\infty dt \exp(-xt)/t.
pub fn E1_e(x: f64) -> (enums::Value, ::types::Result) {
    let mut result = unsafe { zeroed::<ffi::gsl_sf_result>() };
    let ret = unsafe { ffi::gsl_sf_expint_E1_e(x, &mut result) };

    (ret, ::types::Result{val: result.val, err: result.err})
}

/// This routine computes the second-order exponential integral E_2(x),
/// 
/// E_2(x) := \Re \int_1^\infty dt \exp(-xt)/t^2.
pub fn E2(x: f64) -> f64 {
    unsafe { ffi::gsl_sf_expint_E2(x) }
}

/// This routine computes the second-order exponential integral E_2(x),
/// 
/// E_2(x) := \Re \int_1^\infty dt \exp(-xt)/t^2.
pub fn E2_e(x: f64) -> (enums::Value, ::types::Result) {
    let mut result = unsafe { zeroed::<ffi::gsl_sf_result>() };
    let ret = unsafe { ffi::gsl_sf_expint_E2_e(x, &mut result) };

    (ret, ::types::Result{val: result.val, err: result.err})
}

/// This routine computes the exponential integral E_n(x) of order n,
/// 
/// E_n(x) := \Re \int_1^\infty dt \exp(-xt)/t^n.
pub fn En(n: i32, x: f64) -> f64 {
    unsafe { ffi::gsl_sf_expint_En(n, x) }
}

/// This routine computes the exponential integral E_n(x) of order n,
/// 
/// E_n(x) := \Re \int_1^\infty dt \exp(-xt)/t^n.
pub fn En_e(n: i32, x: f64) -> (enums::Value, ::types::Result) {
    let mut result = unsafe { zeroed::<ffi::gsl_sf_result>() };
    let ret = unsafe { ffi::gsl_sf_expint_En_e(n, x, &mut result) };

    (ret, ::types::Result{val: result.val, err: result.err})
}

/// This routine computes the exponential integral Ei(x),
/// 
/// Ei(x) := - PV(\int_{-x}^\infty dt \exp(-t)/t)
/// 
/// where PV denotes the principal value of the integral.
pub fn Ei(x: f64) -> f64 {
    unsafe { ffi::gsl_sf_expint_Ei(x) }
}

/// This routine computes the exponential integral Ei(x),
/// 
/// Ei(x) := - PV(\int_{-x}^\infty dt \exp(-t)/t)
/// 
/// where PV denotes the principal value of the integral.
pub fn Ei_e(x: f64) -> (enums::Value, ::types::Result) {
    let mut result = unsafe { zeroed::<ffi::gsl_sf_result>() };
    let ret = unsafe { ffi::gsl_sf_expint_Ei_e(x, &mut result) };

    (ret, ::types::Result{val: result.val, err: result.err})
}

/// This routine computes the integral Shi(x) = \int_0^x dt \sinh(t)/t.
pub fn Shi(x: f64) -> f64 {
    unsafe { ffi::gsl_sf_Shi(x) }
}

/// This routine computes the integral Shi(x) = \int_0^x dt \sinh(t)/t.
pub fn Shi_e(x: f64) -> (enums::Value, ::types::Result) {
    let mut result = unsafe { zeroed::<ffi::gsl_sf_result>() };
    let ret = unsafe { ffi::gsl_sf_Shi_e(x, &mut result) };

    (ret, ::types::Result{val: result.val, err: result.err})
}

/// This routine computes the integral Chi(x) := \Re[ \gamma_E + \log(x) + \int_0^x dt (\cosh(t)-1)/t] , where \gamma_E is the Euler constant (available as the macro M_EULER).
pub fn Chi(x: f64) -> f64 {
    unsafe { ffi::gsl_sf_Chi(x) }
}

/// This routine computes the integral Chi(x) := \Re[ \gamma_E + \log(x) + \int_0^x dt (\cosh(t)-1)/t] , where \gamma_E is the Euler constant (available as the macro M_EULER).
pub fn Chi_e(x: f64) -> (enums::Value, ::types::Result) {
    let mut result = unsafe { zeroed::<ffi::gsl_sf_result>() };
    let ret = unsafe { ffi::gsl_sf_Chi_e(x, &mut result) };

    (ret, ::types::Result{val: result.val, err: result.err})
}

/// This routine computes the third-order exponential integral Ei_3(x) = \int_0^xdt \exp(-t^3) for x >= 0.
pub fn _3(x: f64) -> f64 {
    unsafe { ffi::gsl_sf_expint_3(x) }
}

/// This routine computes the third-order exponential integral Ei_3(x) = \int_0^xdt \exp(-t^3) for x >= 0.
pub fn _3_e(x: f64) -> (enums::Value, ::types::Result) {
    let mut result = unsafe { zeroed::<ffi::gsl_sf_result>() };
    let ret = unsafe { ffi::gsl_sf_expint_3_e(x, &mut result) };

    (ret, ::types::Result{val: result.val, err: result.err})
}

/// This routine computes the Sine integral Si(x) = \int_0^x dt \sin(t)/t.
pub fn Si(x: f64) -> f64 {
    unsafe { ffi::gsl_sf_Si(x) }
}

/// This routine computes the Sine integral Si(x) = \int_0^x dt \sin(t)/t.
pub fn Si_e(x: f64) -> (enums::Value, ::types::Result) {
    let mut result = unsafe { zeroed::<ffi::gsl_sf_result>() };
    let ret = unsafe { ffi::gsl_sf_Si_e(x, &mut result) };

    (ret, ::types::Result{val: result.val, err: result.err})
}

/// This routine computes the Cosine integral Ci(x) = -\int_x^\infty dt \cos(t)/t for x > 0.
pub fn Ci(x: f64) -> f64 {
    unsafe { ffi::gsl_sf_Ci(x) }
}

/// This routine computes the Cosine integral Ci(x) = -\int_x^\infty dt \cos(t)/t for x > 0.
pub fn Ci_e(x: f64) -> (enums::Value, ::types::Result) {
    let mut result = unsafe { zeroed::<ffi::gsl_sf_result>() };
    let ret = unsafe { ffi::gsl_sf_Ci_e(x, &mut result) };

    (ret, ::types::Result{val: result.val, err: result.err})
}

/// This routine computes the Arctangent integral, which is defined as AtanInt(x) = \int_0^x dt \arctan(t)/t.
pub fn atanint(x: f64) -> f64 {
    unsafe { ffi::gsl_sf_atanint(x) }
}

/// This routine computes the Arctangent integral, which is defined as AtanInt(x) = \int_0^x dt \arctan(t)/t.
pub fn atanint_e(x: f64) -> (enums::Value, ::types::Result) {
    let mut result = unsafe { zeroed::<ffi::gsl_sf_result>() };
    let ret = unsafe { ffi::gsl_sf_atanint_e(x, &mut result) };

    (ret, ::types::Result{val: result.val, err: result.err})
}